Not sure about the thongs, but I do always wonder when people talk about bras being uncomfortable, why that would be.
I wear M&S minimiser bras, and I scarcely notice having one on, even though it's underwired.
I did buy a few from Bravissimo but gave up wearing them as the strap size that was allegedly right for me, was so uncomfortable and dug in a lot.
So doubtless if I wore a different bra, my boobs could look more perky, but frankly I couldn't be arsed with it.